Italian journal of neurological sciences最新文献

The term "consciousness", so widely used in clinical settings, is considered extremely complex and practically undefinable. Historically, consciousness was ignored by the great classical philosophers, and was regarded as a basic condition of "being". This changed with Descartes and during the ensuing centuries. A simplified, reductionistic and easily definable concept of consciousness is proposed; consciousness is proposed to consist of three main components: vigilance, mental contents, and selective attention. These three components can be investigated with modern neuroscientific methods--vigilance being the most readily explorable function. The striking differences between sleep and coma are pointed out (along with some observations on sleep initiation). Special attention is paid to epileptic impairment of consciousness and, in particular, to the spike-wave absence which is thought to be due to a temporary suspension of the "working memory circuits" within the frontal lobe.

We treated 54 patients, newly diagnosed for glioblastoma, with systemic chemotherapy (carmustine (BCNU) 100 mg/m2 and cisplatin 90 mg/m2 every 6 weeks) and radiotherapy soon after surgery. In 10 cases the treatment was combined with locoregional chemotherapy (1 mg bleomycin on days 1-2, and 3 mg mitoxantrone on day 3, repeated every 20 days) administered from an Ommaya reservoir. At tumor recurrence, all patients were treated with procarbazine, lomustine and vincristine (PCV); 15 of 54 were reoperated and treated with locoregional chemotherapy. The median time to disease progression (TTP) and overall survival time (ST) for the whole group were 10.8 and 23.1 months, respectively. The ST of the 15 reoperated patients who also received locoregional treatment at disease recurrence was 27.6 months; this was significantly longer than that of patients not reoperated and not treated locally (log-rank p=0.04). The results in our reoperated subgroup support the opinion that a second operation could be suitable if it is part of the whole program of treatment.

We report the case of a patient who underwent radiotherapy of the neck because of an epidermoid carcinoma in Rosenmuller's fossa. Eleven months later, T1-weighted brain magnetic resonance imaging (MRI) revealed a bulbo-pontine lesion, and the clinical course and sequential MRI results led to a diagnosis of radionecrosis-induced rhombencephalopathy. At a distance of more than three years, the lesion is no longer visible on MRI images but the severe neurological deficits remain. The clinical picture has not been improved by treatment with prednisone, hyperbaric oxygen, symptomatic therapies or anticoagulants.

Neuroimaging techniques aimed at studying structural changes of the brain may provide useful information for the diagnosis and the clinical management of patients with dementia. Magnetic resonance imaging (MRI) may show abnormalities amenable to surgical treatment in a significant percentage of patients with cognitive impairment. MRI may also assist the differential diagnosis in dementia associated with metabolic or inflammatory diseases.MRI has the potential to detect focal signal abnormalities which may assist the clinical differentiation between Alzheimer's disease (AD) and vascular dementia (VaD). Severe temporal atrophy, hyperintensities involving the hippocampal or insular cortex, and gyral hypointense bands are more frequently noted in AD. Basal ganglionic/thalamic hyperintense foci, thromboembolic infarctions, confluent white matter and irregular periventricular hyperintensities are more common in VaD. The high sensitivity of MRI in detecting T2 hyperintense lesions and the low specificity off white matter lesions have resulted in a poor correlation between MRI findings and both neuropathological and clinical manifestations. In particular, MRI has disclosed a series of white matter focal changes in the elderly population, which are not necessarily associated with cognitive dysfunction. The recent advent of a new MRI method sensitive to the microstructural changes of white matter, the so-called diffusion tensor imaging, may be helpful in correlating clinical manifestations with white matter abnormalities.

Neurophysiological methods, such as electroencephalography (EEG) and event-related potentials, are useful tools in the investigation of brain cognitive function in normal and pathological conditions, with an excellent time resolution when compared to that of other functional imaging techniques. Advanced techniques using a high number of EEG channels also enable a good spatial resolution to be achieved. This, together with the possibility of integration with other anatomical and functional images, may increase the ability to localize brain functions. Spectral analysis of the resting EEG, which gives information on the integrity of the cortical and subcortical networks involved in the generation of cortical rhythms, has the limitation of low sensitivity and specificity for the type of cognitive impairment. In almost all types of dementia, decreased power of the high frequencies is indeed observed in mild stages, accompanied by increased power of the slow rhythms in the more advanced phases. The sensitivity for the detection of spectral abnormalities is improved by studying centroid modifications. More specific information on the type of dementia can be provided by coherence analysis of the resting EEG, a measure of functional cortico-cortical connections, which has different abnormal patterns in Alzheimer's disease, cerebrovascular dementia and dementia associated with multiple sclerosis. Another tool for improving the assessment of demented patients is the study of EEG activity related to particular tasks, such as event-related potentials and event-related desynchronization/synchronization of the EEG, which allow the study of brain activation during cognitive and motor tasks.

Positron emission tomography (PET) and single photon emission tomography (SPET) offer the opportunity to improve a diagnosis of dementia by providing regional functional measurements, which can be used to substantiate the clinical judgement. Further progress in the differential diagnosis among degenerative dementias is expected from pathological confirmation in the follow-up of patients evaluated with neuroimaging methods. A prospective multi-center cohort study of patients with possible or probable Alzheimer's disease mostly with presenile onset, showed impairment of brain glucose metabolism in temporoparietal or frontal association areas, as measured with PET. This was associated significantly with dementia severity, clinical classification, presence of multiple cognitive deficits, and history of progression. In addition, prospective longitudinal analysis showed a significant association between initial metabolic impairment (metabolic ratio = 0.80) and subsequent clinical deterioration. In patients with mild cognitive deficits at entry, the risk of deterioration was up to 4.7-times higher if metabolism was severely impaired than with mild or absent metabolic impairment. In the future, it might be possible to use different tracers to measure neurotransmitter release or receptor function. It may also be possible to scan the patient while performing cognitive tasks to examine changes in functional brain activity during pharmacological treatments.

The role of magnetic resonance imaging (MRI) in multiple sclerosis (MS) has received considerable attention in recent years. MRI has the potential to provide indices of disease activity and progression in clinical trials. Moreover, there is now widespread agreement that conventional MRI sequences are useful not only in diagnosing the disease but also in evaluating the natural course of the disease and the response to therapy. Conventional spin echo (CSE) sequences are widely accepted as sensitive techniques for the evaluation and quantification of brain MS lesions. Fast spin echo (FSE) sequences are now used as an alternative to CSE. They have the advantage of a considerable reduction in imaging time. Fast-fluid attenuation inversion recovery (fast-FLAIR) sequences, in which the signal from cerebrospinal fluid is suppressed, also provide a reliable means to evaluate the total lesion burden in patients with MS. Despite some limitations in the detection of infratentorial lesions, Fast-FLAIR sequences are useful in clinical studies. Compared with lesions load on conventional T2-weighted sequences, an increase in hypointense lesion load on CSE T1-weighted sequences correlates more strongly with increased disability in MS patients. This might be an additional useful MRI parameter to monitor disease progression in long-term studies. Gadolinium-enhanced T1-weighted images provide highly sensitive markers for detecting MRI activity, which represent the primary MRI endpoint for screening promising disease-modifying therapies, especially in phase II trials.

Proton magnetic resonance spectroscopy ((1)H-MRS) is considered a suitable investigation technique for obtaining in vivo information on pathological changes in multiple sclerosis (MS) brain. The main betabolites identified are choline-containing compounds, creatine, N-acetylaspartate (NAA), lactate, mobile lipids, myo-inositol, glutamate and glutamine. Proton spectra may be acquired from localized volumes of interest on single MS lesions or from the entire brain by (1)H-MRS imaging. An increase of choline and lipids (markers of demyelination) and the presence of lactate (marker of acute inflammatory reaction) have been demonstrated in active Gd-enhancing MS plaques. A reduction of NAA (marker of neuronal or axonal damage) has been found in inactive MS lesions. The recent evidence of an early NAA decrease in active plaques and in normal appearing white matter suggests that axonal damage is an early event in the evolution of demyelinating lesions. The correlation between NAA decrease and clinical disability conforms that axonal damage has important functional consequences, and indicates that the prevention of irreversible axonal loss might be a major target for the design and the timing of therapeutical strategies.